title: Lack of nontargeted effects in murine bone marrow after low-dose in vivo X irradiation.
abstract: Exposure to high doses of ionizing radiation unequivocally produces adverse health effects including malignancy. At low doses the situation is much less clear, because effects are generally too small to be estimated directly by epidemiology, and extrapolation of risk and establishment of international rules and standards rely on the linear no-threshold (LNT) concept. Claims that low doses are more damaging than would be expected from LNT have been made on the basis of in vitro studies of nontargeted bystander effects and genomic instability, but relevant investigations of primary cells and tissues are limited. Here we show that after low-dose low-LET in vivo radiation exposures in the 0-100-mGy range of murine bone marrow there is no evidence of a bystander effect, assessed by p53 pathway signaling, nor is there any evidence for longer-term chromosomal instability in the bone marrow at doses below 1000 mGy. The data are not consistent with speculations based on in vitro nontargeted effects that low-dose X radiation is more damaging than would be expected from linear extrapolation.
authors.affiliation: Centre for Oncology and Molecular Medicine, Ninewells Hospital and Medical School, Dundee DD1 9SY, Scotland, United Kingdom.
authors.forename: Nikolay A
authors.initials: NA
authors.lastname: Zyuzikov
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Coates
authors.forename: John M
authors.initials: JM
authors.lastname: Parry
authors.forename: Sally A
authors.initials: SA
authors.lastname: Lorimore
authors.forename: Eric G
authors.initials: EG
authors.lastname: Wright
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D024201:Bystander Effect / Q000528:radiation effects; D043171:Chromosomal Instability / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D018499:Linear Energy Transfer; D051379:Mice; D011829:Radiation Dosage; D015398:Signal Transduction / Q000528:radiation effects; D013312:Stress, Physiological / Q000528:radiation effects; D013997:Time Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014965:X-Rays
chemical_list: D016159:Tumor Suppressor Protein p53